1. Field of the Invention
The present invention relates to a YC separation system, and more particularly to a 2D YC separation device and a YC separation system utilizing the 2D YC separation device.
2. Description of the Related Art
FIG. 1 is a schematic view of a conventional YC separation device. The conventional YC separation device 10 is used to separate a composite signal into a luma signal and a chroma signal. The conventional YC separation device 10 comprises a row delay circuit 11, a subtractor 12, an adder 13, a first halving circuit 14, and a second halving circuit 15.
The composite signal is a video signal, which can be an NTSC composite signal or a PAL composite signal. Taking the NTSC composite signal as an example, the composite signal can be represented as V=Y+I cos(wt)+Q sin(wt), wherein Y is a luma signal, I cos(wt)+Q sin(wt) is a chroma signal (C), and thus V=Y+C. The conventional YC separation device 10 assumed that the luma signal and the chroma signal of two horizontal scanning lines with one above the other are the same. If the composite signal is V2=Y2+C2, it will become V1=Y1+C1 after passing through the row delay circuit 11, wherein C2=−C1 due to the time difference between scanning signals, and then V1=Y2−C2. That is, the composite signal through the row delay circuit 11 is equivalent to the composite signal of a previous horizontal scanning line.
The subtractor 12 is used for subtracting the delayed composite signal V1 from the composite signal V2 (V2−V1), thus obtaining a doubled chroma signal (2×C2). Then, the doubled chroma signal (2×C2) is divided by 2 via the first halving circuit 14, thereby obtaining the chroma signal C2.
The adder 13 is used for adding the delayed composite signal V1 to the composite signal V2 (V2+V1), thus obtaining a doubled luma signal (2×Y2). Then, the doubled luma signal (2×Y2) is divided by 2 via the second halving circuit 15, thereby obtaining the chroma signal Y2.
As for the conventional YC separation device 10, it is assumed that values for the luma signal and the chroma signal of two horizontal scanning lines with one above the other are the same, that is, Y1=Y2, |C1|=|C2|, such that the luma signal and the chroma signal can be correctly separated. Therefore, if the values for the luma signal and the chroma signal of two horizontal scanning lines with one above the other are different, the luma signal and the chroma signal can't be correctly separated by utilizing the conventional YC separation device 10.
Thus, it is necessary to provide a novel and creative YC separation device to overcome the above-mentioned problems.